At present, there are two major methods for testing the performances of Printed Circuit Boards (PCB) or Multi Chip Modules) MCM), either during or after the manufacturing process. One of those methods is commonly known in the art as ‘the bed of nails method’ and another is a method commonly known in the art as ‘the flying probe method’.
The bed of nails is a resistance measurements method comprised of springy pins, which are electrically connected to ports on the PCB/MCM. During the test signals are applied to some of the nails, and measurements are taken at other nails. The bed of nails device needs to be especially designed, built and programmed to fit the structure of the tested PCB/MCM type. Each type of PCB/MCM requires a different device.
The flying probe method is based on moving pair(s)' probes physically from one point to another, touching the board and sequentially conducting the same tests made by the bed of nails. This method eliminates the need to build the physical element required by the bed of nails method, but it still requires making physical contact with the board while conducting electrical tests. Bed of nail tests is limited to a minimum pitch size of 600 micrometer. The method of testing PCBs by flying probe is limited to a minimum pitch size of 300 micrometers. The bed of nails test time can take between 1 and 2 minutes per PCB/MCM, for flying probes the test time is more than two hours.